Mastering Wort Boiling: Essential Techniques for Brewing Better Beer

In the performance of wort boiling two aspects are of particular importance and they are

inter-related:

• the boiling of the wort and
• the conversion of hop-bittering compounds.

Beer Brewing: Boiling the wort

In general, boiling is commenced as soon as the wort is in the kettle.

Boiling is performed today for 40 to 50（sometimes 60）min.

It is preferable not to boil for a long time and vigorously because:

• the coagulable protein should not be completely precipitated,
• the DMS is nevertheless driven out,

and because the energy costs increase with each minute of boiling and are therefore not performed any longer than necessary. Consideration has to be given to the dissolving and isomerization of the hop-bittering substances which only dissolve more thoroughly with increasing length of time.

It is however important that the wort at the end of the boiling process, in other words at casting, has reached the desired extract content since only in this way can the desired original wort gravity be achieved. This must be born in mind before beginning the boiling process.

It is also important to check again that saccharification is complete before beginning the boil.

It is possible that during mashing-off and lautering more starch components have gone into the Solution and have not been saccharified because the amylases were already inactivated by the high:(perhaps even too high!）final mashing temperature. To avoid a starch haze in beer a supplementary saccharication must be performed before heating in the wort kettle or in the fermenting cellar by the addition of first wort or malt extract-it cannot be corrected later.

Hop addition

The hops are added during wort boiling and boiled with the wort. During boiling the insoluble α-acids are isomerized to soluble iso-acids which give a bitterness to the beer. It is the-

by important to know:

• what quantity of hops must be added,
• when the hops should be added, and
• how the hops can be added to the wort.

Calculation of the hop addition

A bitterness is sought which corresponds to the beer type. Bitterness is expressed in

Bitterness units （BU）= mg of bitter substances/l of beer.

Average bitterness unit values and bitter substance additions for German beers are, for example:

Thus to produce a Pilsner beer with 32BU, the target is 32mg bitter substance per 1 of beer. The hops are added to the hot wort. This wort contracts on cooling by 4%. The quantity of hops to be added has now to be calculated based on the amount of cold beer to be cast.

There is also another important factor. Only part of the bitter sustenance introduced goes into the beer. This bitter substance yield depends on the particular operating conditions(boiling time, pressure, pH， etc)and varies in general between 25 and 35%, calculated on the finished beer. Inspection of the table shows that the amount in grams of α-acid to be added to the wort is always about a third of the bitterness units wanted in the beer. For an exact addition, however, this bitterness yield must be determined by trials in the brewery.

The next step is that the α-acid must be divided amongst the individual hop additions and products. This requires a decision by the brewery.

Composition of the hop addition and time of addition

Three different types of products are available for the hop addition:

• whole leaf hops，
• hop pellets, and
• hop extracts.

There are hardly any quality differences between these products nowadays because all the production processes very carefully protect the desired hop contents. There are however quality

differences between individual hop varieties as already mentioned.

Nowadays it is the size and equipment of the brewhouse which decides what products are used. Overall an increasing turning away from the use of whole-leaf hops can be seen, since their use results in the occurrence of spent hops which must be removed.

With regard to hop addition, points to consider are:

• in how many parts the additions should be made,
• when the partial additions should be made, and
• which varieties first, which last.

When several varieties are used, the bittering hops are always added first in order to isomerize their high α-acid potential as much as possible. Moreover, undesirable volatile components are driven off.

The hops with the best aroma–the aroma hops–are added last, at the end of boiling or even in the whirlpool, whereby the whirlpool temperature should be lower to 80℃. Thereby the desirable hop oils are retained for the beer if this is desired for the beer in question. However the maximum utilisation of the α- acids must be foregone in this case.

There are a number of advantages to proceeding in this way:

• better beer foam (up to 10 points according to R&C),
• higher yield of iso-α-acids,
• higher charge of unisomerised iso-α-acids(about 2.7mg α-acid/l)；this results in higher micro biological stability.

The decision of which hop additions are made affects the quality of the beer produced.

Conclusion

Mastering the art of wort boiling and hop addition is essential for producing exceptional beer. By understanding the intricacies of these processes—such as timing, temperature, and ingredient selection—brewers can consistently craft beers that stand out in flavor, aroma, and quality. Whether brewing a classic Pilsner or a robust Bock beer, attention to detail during wort boiling ensures a memorable drinking experience.